Willett has been a high-profile critic of research into the so-called "
obesity paradox" posited by, among others, American epidemiologist
Katherine Flegal and her colleagues at the
Centers for Disease Control and Prevention's
National Center for Health Statistics, going so far as to call it a "pile of rubbish ... No one should waste their time reading it." In 2013, the journal
Nature ran an editorial rebuking Willett for the style and manner of his criticism, saying it misrepresented the complexity of the science involved and used inappropriate language in doing so. In 2021, Flegal published an article in the journal
Progress in Cardiovascular Diseases accusing Willett and some of his Harvard School of Public Health colleagues of being part of "an aggressive campaign that included insults, errors, misinformation, social media posts, behind-the-scenes gossip and maneuvers, and complaints to her employer." Flegal wrote that the goal Willett and his allies "appeared to be to undermine and discredit her work," and that, "The controversy was something deliberately manufactured, and the attacks primarily consisted of repeated assertions of preconceived opinions." Flegal also questioned Willett's competence to criticize her team's statistical research, as he "was not a statistician and had no expertise in estimating the number of deaths associated with obesity." ==Reception==